Method of preparing skelp for welding



July 2', 1940. .J. E. MARKEY METHOD OF PREPARING SKELP FOR WELDING Filed Nov. 19, 1938 4 4 &J

INVENTOR John &Mar-!rey Patented. July 2, 1940 UNITED STATES METEO!) OF PREPARING SKELP FOB WELDING- John E. Markey, Allquippa, Pa., assinior to Jones & Laughlin Steel Corporation,

` Pa., a co'poration of Pensylvania Application November 19, 1938, Serial No. %1,379

,z Claim. This invention relates generally to the manufacture of welded pipe and, in particular, to the heating of skelp preparatory thereof.

In the man'ufacture of welded pipe according to the' conventional method of heating skelp to welding temperature and drawing it through a welding bell or die, it has been found that the gskelp tends to pick up the material composing m the furnace bottom on which the skelp rests during heating If the furnace is provided with a silica bottom, the material picked up therefrom adheres to the skelp in the form of silica scale and is a frequent cause for the rejection of pipe 15 on inspection. such rejections may amount to as high as 12% of the total production of a pipe mili. The lossrepresented by these rejections has caused considerable eflort to be devoted to the problem without, so far as I am aware, 90 achieving any satisfactory solution therefor.

I have invented a method and apparatus which are effective to reduce the percentage of rejections on account of silica scale to an almost negligible figure. I have discovered that the adherence to' the skelp of the material composing the furnace bottom may be substantially prevented by appropriately controlling the temperature of the bottom. In a preferred practiceof the invention I control the temperature of' the furnace bottom in suchm'anner as to maintain the temperature thereof below' a certain value at which the material, e. g., silica, ex-

to the welding hibits a tendency to adhere to the skelp when heated to welding temperature. My invention also contemplates a novel furnace construction `adapted for the practice'of the method above mentioned. An example of the iurnace structure is illustrated in the accompanying drawing to which reference will'be made for a complete 40 explanation. of my apparatus and method, In

the drawing: i Fig. 1 is a section through a skelp heating furnace embodying the invention. taken on the plane slightly above the fumace bottom; and

Fig. 2 is a partial transverse section along the line II-II of Fig. 1; line I- -I of Fig. 2 indicates the plane along which Fig. 1 is taken.

Referring now in detail to the drawing, a skelp heating furnace o comprises side walls I, end walls !2, and a roof (not shown). The end'walls are provided with suitable openings l3 through which skelp lengths ll may be inserted and removed. The skelp lengths, while in the furnace, rest on the hearth or bottom thereof, indicated 55 at'l; The tumace b ttom is preferably composed of a layer of sand |6 and a layer of grave] i'l supported on a foundation !8 of refractory brick or the like.

cooling ducts s, which may be simply suitable lengths of pipe of appropriate size, are embedded in the sand layer IS with their ends open and protruding beyond the end walls l2, and are adapted, either by natural draft or forced circulation of air or other cooling fluid therethrough, to control the temperature of the furnace bottom. If natural draft through the ducts is relied on for cooling, the number and size of the ducts are so chosen that the resulting draft will have the desired cooling effect. In`this' case, the ducts will be connected by any suitable means `(not shown) to an exhaust stack. If forced circulation of coolingrfiuid through the ducts is employed. the desired control over the temperature of the furnace body may be eifected by varying the rate of fluid circulation. In this case, any known means such as fans, blowers, or 4 the like, may be used to produce the desired cir- 'culation.

In practicing the invention with the aid of the apparatus described hereinabove, I deposit skelp lengths onthe fumace bottom li for heating preparatory to passage through a welding bell or die. The furnace ID may be heated in any convenient manner, e. g., by suitable fuel burners arranged therein in the known manner. The furnace is operated so that the skelp charged thereinto will be heated to the welding temperature within the desired time. When the skelp has been properly heated, it is withdrawn from the furnace and passed through the welding die.

By means of the ducts !9, I so control the temperature of the furnace bottom as to maintain it below that at which silica scalefrom the material composing the furnace bottom adheres 'to the heated skelp and is picked up by the latter 40 as it is withdrawn from the furnace for welding. The exact temperature of the bottom at which the skelp picks up silica scale is variable as it depends largely on local conditions. In any event, sufiicient cooling can be had by the means shown to prevent almost entirely the objectionable adherence of silica experienced previously. In the typical furnace construction illustrated, I have found that for a furnace about 8' wide. eight 7" pipes arranged as shown in the' drawing are sufflcient to provide suilicient cooling by natural draft to reduce the objectionable adherence of silica scale to the skelp to an almost negligible amount. a v

By the aid of the invention, it has been possible ably. By substantially eliminating the withdraw- I "al oi the material composing the furnace bottom with the skelp. furnace bottoms last longer than heretofore and require renewal les often. The invention thus provides a relatively simple and inexpen !ve solution for the difiiculty experienced heretofore with silica scale which, so far as I am aware, has not previously been obtained despite numerous efforts extending over a. substantial period of years.

Although I have illustrated and described but a preterred form and practice of the inventio'n, it will be understood that changes in the structure and procedure disclosed may be made withv out departing from the, spirit of theinvention or the scope ot the appended claims.

I claim:

1. In a method oi preparing skelp tor welding to form pipe, the steps including providing a furnace bottom composed of granular silica, placing 'the skelp on said bottom, heating the skelp to welding ,temperature while on said bottom, and admitting cooling`fluid to the interier ci the mass oi granular silice comprising the bottom, thereby cooling it to a temperature below that at which the granular silica forms a glaze on the skelp.

2. The method of pr'eventing the formation of silica scale on skelp in the manufacture of welded pipe wherein the, skelp is heatedto welding temperature in. aiurnece having a. granular siiica. bottom, which method consists in maintaining said bottom at a temperature below that at which the silica of the bottom forms a glaze on the skelp, by circulating cooling fluid through the silica bottom.

JOHN E. MARKEY. 

